This invention relates to electrical insulators, and in particular to insulators used in attaching heat sink assemblies comprising heat generating electronic components and heat dissipators to printed circuit boards. This invention is to some extent related to an invention described in application Ser. No. 434,816 filed Oct. 18, 1982, which is assigned to the assignee of the present invention. The No. 434,816 application is incorporated herein by reference.
The earlier application discloses a novel fastener which assures thermal conductivity between a heat generating component and a heat sink. In some circuit designs, however, it is desirable to attach a plurality of such components to a single heat sink. In many heat generating components, the base or support of the component also serves as a terminal for the component. In many transistors the collector terminal is connected to a circuit through mounting hardware. The mounting hardware, is in effect, a circuit element. If a plurality of components are attached to a single heat sink, the heat sink will tend to allow current to flow directly between the components. It is therefore sometimes necessary to mount components in such a way as to promote thermal conductivity, while at the same time preventing electrical conductivity, between the components and the heat sink.
Accordingly, it is an object of the present invention to provide an electrical insulator which is able to be preassembled to a fastener used to connect components to a heat sink.
Another object is to provide an insulator which is capable of withstanding continuous clamp load between heat sinks and mounting fasteners while maintaining electrical isolation between them.
Yet another object is to provide a preassembled fastener and insulator combination which facilitates assembly of heat generating electrical components to a heat sink while preventing short circuits among the components.
Still another object of the invention is to provide a heat sink assembly having a plurality of components which may be quickly and easily connected to a printed circuit board.
These and other objects and advantages are achieved with an insulator which is preassembled to an electrically conductive fastener. The insulator may be made of plastic or it may be metallic with a non-conductive coating, such as hard anodized aluminum. Either the fastener or the insulator preferably has an integral spring flange to maintain clamp load and thermal conductivity between components and an associated heat sink. In a heat sink assembly having a plurality of components, the insulators are positioned generally at the interface between the conductive fastener and the heat sink. Preferably, the insulator has a boss which extends into an aperture in the heat sink.
The various embodiments of the present invention will be better understood upon a reading of the following specification read in conjunction with the attached drawings.